Process of reducing zinc ores



(No Model.) 2 Sheets-Sheet 1.

E. WALSH, Jr.

PROCESS OF REDUOING ZING ORES.

No. 364,979. Patented June 14, 1887.

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No. 364,979. Patented June 14, 1887 N. PETERS. Phntu-limogliphnr. washinmn. D. c.

UNITED STATES ATENT 'FFICE.

EDVARD \VALSII, JR., OF ST. LOUIS, MISSOURI.

PROCESS OF REDUCING ZINC ORES.

SPECIFICATION forming part of Letters Patent No. 364,979, dated June 14,1887.

Application filed April 16, 1886.

To all whom it may concern:

Be it known that I, EDWARD ALSH, J r., a citizen of the United States,residing in the city of St. Louis, State of Missouri, have made acertain new and useful discovery in the art relative to the reduction ofthe oxide of zinc in native or calcined zinc ores, of which thefollowing is a full, clear, and exact description.

Oxide of zinc is ordinarily obtained from the natural zinc ore by threeprocessesthe Belgian, the Silesian, and the English-the last of which isnearly obsolete. The Belgian and Silesian have the same general mannerof accomplishing the result, and the choice of one or the other dependsupon local circumstances-via, prices of fuel, class of ore, and also theamount of metallic zinc contained in the ores. They both use smallretorts, cylindrical in shape, heated externally either by a Siemensgas-furnace or hand-fired furnace. Into the retorts is charged themixture of calcined ores and fuel, and the distilled zinc is collectedor condensed in the prolongation of the retort, which is firmly lutedonto the end of the retort outside of the furnace. These processes arevery wasteful and very laborious; but the processes which I have statedabove are those which are inuuiversal use today, notwithstanding thegreat expense and waste connected with them.

I am aware that attempts have been made to treat zinc ores in a blast orcupola furnace, my attention having been called to United States LettersPatent to Adrian Muller, No. 32,840, dated July 16, 1861, and UnitedStates Letters Patent to Amedee G. Sebillot, No. 291,410, of January 1,1884; but in practice the devices described in the said several LettersPatent will be found not to be operative for the purpose ofreducing-oxide of zinc in ores, the conditions appertaining to a blastor cupola furnace and the temperatures at which the various reactionstake place not having been provided for.

In regard to the Muller patent, theinventor describes, as one step inhis process, the molding of materials into blocks, &c. This is anunnecessary expense and is detrimental to the process, inasmuch as itinterferes with the proper combustion of the fuel as it approaches thetuyeres; and, furthermore, in order to ag- Serial No. 199,149. (Nomodel.)

glomcrate the materials, it would be necessary to crush the fuel, andthe universal experience with the blast-furnace or cupola-furnace hasshown that powdered fuel does not give good action in the furnace.Furthermore, the introduction of carbonic oxide about the middle of thefurnace, as stated by Muller in his specification, not only is anexpensive thing to do by the means set forth, but it is a positivedisadvantage. It only tends to interfere with the action of the blowingapparatus, and can have no effect in promoting a downward tend ency ofthe vapor, inasmuch-as, after deducting the friction of its passagethrough a long conduit, and a diminishing pressure, due to partialescape of the gases from the condenser, its pressure will be so greatlydiminished that, instead of retarding the upward flow or driving downthe vapors, it will afford an upward passage for the vapor therebyseriously inter- 'l'ering with the process. Another serious objection tothis method of Mr. Mullers is that at the level at which the gases arewithdrawn the numerous openings form a means of very rapidly destroyingthis portion of the furnace. In fact, it would be impossible to findmaterial sufficiently refractory to withstand the intense heat at thepoint of the furnace at which he withdraws his gases.

Mr. Sebillot, in his patent above referred to, has not solved theproblem of manufacturing metallic zinc in a blast or cupola furnace, forreasons which will more clearly appear in describing my invention. It istrue, as he states, that attempts in this direction have hereto forebeen a failure, as the vapors of zinc are immediately converted intooxide of zinc by the very smallest quantity of carbonic acid; but hedoes not describe an apparatus which will convey clean vapors of zincinto the con denser, freefrom carbonic acid. Hislowereduction-orifices,as stated by him, are situated in the very hottest part of the furnace,at a point where the temperature would be about 3,000 Fahrenheit. Thistemperature is so great that it will destroy the arrangement of deviceswhich he has provided for keeping the char coal G at a red heat. 7 Aswill be appreciated from reading adescription of my invention, his lowercduction-orifice is at an unnecessarily low point in the furnace and ata point at which it would be a practical impossibility for the operationwhich he described to take place.- This shows that the conditionspertaining to a blast-furnace are not appreciated by the inventor, andthat the question of temperatures at which the various reactions takeplace (essential features guarded against and provided for in myinvention) was not considered by him. Furthermore,- in the furnacedescribed by Mr. Sebillot the zinc ore charged in the top of the furnacewill of necessity be reduced and volatilized in the higher and coolerportions of the furnacc, and the zinc will be oxidized'in these higherand cooler portions of the furnace by the atmospheric air, and themoisture contained in the fuel and the carbonic acid generated in thereduction of the zinc oxide will be carried into theuppereduction-orifice or outlet-pipe and into the condenser. g V

In my invention the conditions pertaining to a blast or cupolafurnaceand the degrees of temperature at which thevarious reactions take placeare considered. Zinc oxide reduces at 1,300 Fahrenheit, and the metaldistills at about 100 Fahrenheit lower than that temperature.Volatilization takes place immediately on reduction of the zinc oxide.

At a temperature of 1,300 Fahrenheit car bon is entirely unaffectedbythe action of carbonic acid, and the carbonic acid generated from thereduction of the zinc oxide is carriedoff' with the zinc vapor at thattemperature. Carbonic acid at a temperature below 1,300

Fahrenheit, when mixed with zinc vapor again oxidizes the metallic zincvapor, thereby producing an undesirable result; but'I have discoveredthat when zinc vaporandcarbonic acid, both at a temperature of between1,400 Fahrenheit and 1,500 Fahrenheit, or slightly in excess of thattemperature, are allowed to pass ;through carbon or carbonaceous matter,which is also at a temperature of between 1,400 Fahrenheit and 1,500".Fahrenheit, the

carbonic acid is immediately converted into carbonic oxide, and .thatthus the zinc vapor does not undergo any further oxidation; that theresult of thus allowing carbonic acid and zinc vapor at the temperatureof between 1,400 Fahrenheit and 1,500 Fahrenheit, or slightly in'excessof that temperature, to pass through carbon or carbonaceous matter at atemperature between 1,400 Fahrenheit and 1,500 Fahrenheit, or slightlyin excess of that temperature, is to produce zinc vapor and carbonicoxide. I have utilized this discovery of the various temperatures atwhich these reactionstake place, together with my knowledge of theconditions pertaining to furnaces, so as.

to reduce metalliczinc in cupola-furnaces.

- I utilize a cupola-furnace of special design for the purpose, asillustrated by the accompanying drawings, on which- Figure 1, Sheet 1,is a sectional elevation of the furnace audits appurtenances; Fig. 2,

Sheet 1, a plan thereof, and Fig. 3, Sheet 2, an endview thereof withtop portions removed;

Fig. 4., Sheet 2, a sectional elevationxof the furnace on a plane atright angles to that in Fig. 1, and charged with fuel and ores.

In the drawings, A represents the furnace, 3 into which the fuel andcalcinedzinc ores, mixed in such proportions that sufficient fuel ispresent to effect a reduction of the zinc oxide to volatilize the zincand fuse the prop-- erly-fiuxcd impurities contained in the ore, arecharged through the hopper and chute B. The proportion of fuel to orewill be about one thousand pounds of fuel to a gross ton of ore, theproportion depending on the quality of ore and fuel and the constructionof the furnace, g i

enough to insure a delivery of the mixed fuel and ores at a point in thefurnace where the temperature of the material is at 1,500 Fahrenheit, orslightly in excess of that temperature, and yet not so far into thefurnace as to exg, pose the chute to the most intense heat of thefurnace, where its parts would be destroyed.

In my chute B the mixed fuel and ores, be I tween the point of chargingand the point of delivery, are in a state of preparation with a View ofpreventing the oxidation of the zinc vapor, the moisture contained inthe fuel and oreare being expelled by the heat,and the contents of thechute as it approaches the point of delivery being gradually heated to atem- 1 perature of about 1,500 Fahrenheit. The sameapplies to the fuelcontained in the auxiliary hoppers D. The effect of this is that themoisture is expelled from the contents of the chutes B and D, and thatthe mixed fuel and :0

ore and fuel are delivered into the furnace in such a condition and atsuch a temperature that the zinc vapor on its way out from the furnaceis not oxidized.

The following is the method of operation: 10 The furnace being put inoperation, when the mixed fuel and ore and also the overlying fuel Ohavereached a temperature of 1,500 Fahrenheit, the zinc vapor and carbonicacid (generated from the previous reduction of the '11 zinc oxide) fromthe calcined ores pass th rougl'r the overlying mass of fuel orcarbonaceous} matter 0, and in so doing the carbonic acidisi immediatelyconverted into carbonic oxi'de,- the effect of which is to produce zincvapor} mo and carbonic oxide, which passoff th'rought} conducting-tube Eto the condenserF, wheretj the zinc vapor is condensed and the carbonicfoxide carried off from the condenser F through pipe G for use, asrequired.

The advantages of my method are these: cheapness and simplicity in theconstruction of the apparatus, certainty of operation, dueconsiderationbeing had to the temperatures, and non-liability todestruction by extreme :30 heat of the parts of the furnace at which thezinc vapor is generated and through which this zinc vapor is conductedto the condenser.

I do not desire to claim, broadly, causing the zinc and other vapors topass through a superincumbent charge of carbonaceous matter,nor do Idesire to claim any particular form or kind of furnace.

I claim I The method of reducing the oxide of zinein ores in cupolafurnaces, consisting in first charging in the furnace the mixed fuel andore in the proportion substantially as specified; second, chargingcarbonaceous matter in the furnace independently of the other charge andat one or more independent points above the mixed fuel and ore; third,causing the carbonic acid and zinc vapors to pass through thesuperincumbent layer of carbonaceous

